Sealed limit switch



June 17, 1969 w. J. RUSSELL SEALED LIMIT SWITCH Filed Sept. 2 1966 Sheetof s FIG-I INVENTOR. 5 I WILLIAM J. RUSSELL- HIS ATTORNEYS June 17, 1969RUSSELL 3,450,855

SEALED LIMIT SWITCH Filed Sept. 2, 1966 Sheet Of 6 I62 I60 I58 I64 FIG-5/7 42 I I60 I58 NVENTOR.

24 32 2 WILLIAM J. RUSSELL EXAM/M H IS ATTORNEYS W. J. RUSSELL SEALEDLIMIT SWITCH June 17, 1969 I Sheet Fi led Sept. 2, 1966 I N VENTOR.WILLIAM J. RUSSELL HIS ATTORNEYS June 17, 1969 w. .1 RUSSELL 7 3,450,855

SEALED LIMIT SWITCH Filed Sept. 2, 1966 Sheet 4 ore INVENTOR. WILLIAM J.RUSSELL HIS ATTORNEYS June 17, 1969 W. J.. us5

SEALED LIMIT SWITCH INVENTOR. WILLIAM J. RUSSELL Filed Sept. 2, 1966 HISATTORNEYS US. Cl. 200-168 13 Claims ABSTRACT OF THE DISCLOSURE Thisapplication discloses a switch casing construction with a switchtherein. Switch power line-s are connected to connecting means or screwson the switch to connect switch power lines for control of one or morecircuits by the switch. A switch access opening is provided on thecasing for access to the switch line connecting means, for attaching theswitch power lines to the switch. A cover is provided for the accessopening, which will be used when the switch casing construction is to beused alone without any plug-in casing. Such switch casing constructioncan be mounted on any support desired, and may operate in the usualmanner. A plug-in casing has prong interlock means in the casing andplug-in power line connecting means for connection of the plug-in powerlines to the interlock means. A plug-in access opening is provided foraccess for the prong interlock means in the plug-in casing. A plug-inchange prong interlock means or construction is provided to replace theswitch power line connecting means, so that the switch casing may bechanged to be connected to the plug-in casing. This is accomplished byomitting the cover and securing the switch casing and the plug-in casingtogether at the access openings and with power lines connected to theplug-in power line connecting means.

This invention relates to a sealed limit switch with plug in changemeans and a plug-in receptacle.

A switch construction, according to this invention, may include a switchcasing with a switch in the casing. A power line switch connector meansmay be provided inside of the casing, with a switch connector accessopening means on the casing for access to such connector means. Suchswitch construction may be used by itself, to be attached to a supportin any suitable manner, as desired.

Additionally, such switch construction may also be used with a plug-incasing and with a plug-in change means, so that the switch constructionmay be plugged into the plug-in casing or receptacle, after the plug-inreceptacle has been connected to a power line.

The construction is such that the plug-in receptacle may be mounted on asupporting surface or board, with the power line or power linesconnected to a connector, or connectors in the plug-in receptacle.Thereafter the switch construction may be plugged in to the plug-inreceptacle, or unplugged therefrom, in an efficient manner.

Further, this invention may include a name plate or cover which may beused with the switch construction alone over the access opening of theswitch construction, and such name plate or cover may be transferred toanother position on the switch casing.

Plug-in change prong means may replace the power line switch connectorsof the switch construction. Then the switch casing and plug-in casingmay be united in a plugged-in manner.

A gasket construction may be used in connection with the name plate orcover on the switch construction when used alone. Additionally, suchgasket may be used benited States Patent 6 F Patented June 17, 1969tween the two casings, when they are united, hermetically to seal boththe switch casing and the plug-in casing.

Other features of this invention are apparent from this description, theappended claimed subject matter, and/or the accompanying drawings, inwhich:

FIGURE 1 is a perspective view of the switch construction when usedalone, without the plug-in casing construction.

FIGURE 2 is a front view of the switch construction of FIGURE 1, inenlarged scale, with the name plate, or cover, and the gasketconstruction removed.

FIGURE 3 is a vertical cross section generally transverse to FIGURE 2,and taken along the line 33 of FIGURE 1.

FIGURE 4 is a vertaical cross section taken generally along the line 4-4of FIGURE 3.

FIGURE 5 is a cross section taken line 55 of FIGURE 4.

FIGURE 6 is a diagrammatic exploded perspective view of the switchconstruction, and the plug-in construction, before they are united intothe assembly condition shown in FIGURE 7.

FIGURE 7 is a vertical cross section, partly in elevation, showing theswitch construction and the plug-in construction of FIGURE 6 in unitedform, and in enlarged scale.

FIGURE 8 is an elevation of the p1ug-in receptacle, along the line 8-8of FIGURE 7.

FIGURE 9 is a cross section taken line 99 of FIGURE 8.

FIGURE 10 is a view somewhat similar to FIGURE 2, with the plug-inchange means or prongs having replaced the power line connector means ofFIGURE 2.

FIGURE 11 is a cross section taken along the line 11-11 of FIGURE 10.

FIGURE 11A is a view of a portion of FIGURE 11, before the plug-in prongconstruction has replaced the power line connector means of FIGURES 2and 3.

FIGURE 12 is a diagrammatic, exploded, perspective generally along thegenerally along the .view of the plug-in receptacle construction beforeit is assembled.

FIGURE 13 is an exploded rear view of the insulating plug-in cupconstruction shown in the central part of FIGURE 12.

FIGURE 14 is a perspective view of the connector holding wall takenalong line 14-14 of FIGURE 12.

FIGURE 15 is a plan view of another embodiment of a plug-in receptacle.

FIGURE 16 is a cross section along line 1616 FIGURE 13.

FIGURE 17 is a perspective exploded view of the lower right hand cornerof a portion of FIGURE 13 and looking in the opposite direction.

Certain words may be used in this specification and claimed subjectmatter which indicate direction, relative position, and the like. Suchwords are used for the sake of brevity and clearness. However, it is tobe understood that such words are intended to be used in connection withthe views of the drawings, and that in actual use, parts so describedmay be in a different direction, relative position, and the like.Examples of such words are verti cal, horizontal, upper, lower, etc.

A switch casing means or construction is generally indicated at 20 inthe various figures. A plug-in casing means or construction is generallyindicated at 22 in the various views. Such switch casing or construction20 may be used independently of the plug-in casing or construction 22,as shown in FIGURES 15. However, certain parts of the switch casing orconstruction 20 may be changed, as hereinafter described, and suchswitch casing or construction 20 may then be used in combination withthe plug-in casing or construction 22, as shown in FIG- URES 6-14, aswill become apparent.

The switch casing or construction 20, as shown in FIG- URES 1-5 may haveany type of suitable switch means 24 inside the casing 20. Switchactuating means or actuator means 26 may actuate the switch inside thecasing and may have operable or operating means 28 outside the casing.Said operating means 28 is mounted on said switch casing 20 andconnected on said casing so that the operating means may be mounted inany one of four different horizontal directions. The operating means 28is mounted on the casing in any suitable manner. For example, screws 29extend through the casing of the operating means and into the casing 20to hold the casing of the operating means 28 firmly on the casing 20.

A switch power supply or power line connector, connectors, or connectingmeans 30 may be provided on the switch 24. Such connecting means mayinclude one or more screws with screw heads. Switch power lines 32 maybe connected to the power line connecting means 30, when the switchconstruction 20 is to be used alone, as shown in FIGURES 1-5. Such powerlines 32 may enter the switch casing 20 through a power line conduit 34,which may be inserted and sealed in the conduit or switch power linereceiving opening means 36. For example, the conduit 34 may be threadedinto the opening 36, and sealed by a gasket at 38. However, the opening36, and the end of conduit 34 may be smooth and may be secured togetherby epoxy adhesive or the like, if desired. The power lines 32 may beinserted in the casing 20 from the conduit 34 and may be secured to thepower line connectors or screws 30 in any well known manner.

A substantially fiat switch access opening means may be provided on onewall of the switch casing 20. Such opening means 40 may be covered by aflexible gasket means 42 and by a cover, means such as a name plate orcover plate 44. The gasket 42, and name plate or cover 44 may be securedover the opening means 40 by means of the screws 46. The screws 46 maypass through openings 97 in the gasket, FIGURE 12, and into threadedholes 47 in casing 20, shown in FIGURE 2. The cover 44 and gasket 42 maybe removed from their positions shown in FIGURES 1 and 3 by removing thescrews 46, and then the power lines 32 may be secured to the connectormeans 30, or may be removed from such connector means 30, as desired.The gasket 42 and cover 44 may then be replaced after removal, asdesired.

When the switch construction 20 is to be used by itself, as shown inFIGURES 15, the casing 20 may be mounted on a supporting surface orboard by means of the mounting screws 48, which may be inserted in theinternally smooth corner openings 50, which extend completely throughthe casing 20, so that the mounting screws 48 may be inserted into andsecured to the mounting board or surface, not shown.

When the switch construction 20 is to be used in combination with theplug-in casing means or construction 22, the parts may be assembled orarranged as shown in FIGURES 6-14.

The plug-in casing or construction 22 may have a permanent pronginterlock means 52 which may be plugin connector, connectors, orconnector means or prong receiving fork members 52. Such connector,connectors, or connector means 52 may be spaced, prong receiving forkmembers somewhat similar to the usual prong-receiving fork connectors ormembers of a usual plug-in receptacle construction. According to thisinvention the fork members 52 may be loosely mounted in the casing 22 toaccommodate themselves to variations in the assembly of the prong points66.

The plug-in casing or plug-in construction 22 may be provided with asubstantially flat plug-in connector access opening means 54, FIGURES 6,7 and 8 which may include the gasket receiving and sealing head 56.

Plug-in change prong interlock means or prongs 58, FIGURES 7 and 11, mayreplace the power line switch connectors 30 of FIGURE 11A. The powersupply connectors or screws 30 may be removed or unscrewed from theswitch construction at 11A, and the plug-in change prong interlock meansor prongs 58, of FIGURE 11, may be screwed in to the receiving sleeveconnectors 158 of the switch construction 20. The prong means 58 mayinclude a screw or threaded portion 62 at one end, an intermediateturning or wrench-receiving portion or hexagonal portion 64, and a prongpoint 66 at the other end. The prong point 66 is insertable into thepower line plugin connector or connectors or prong interlock members 52.It is therefore to be seen that the plug-in change prong means of FIGURE11 replaces the power line switch connector 30 of FIGURE llA.

After the change means or prongs 58 have replaced the switch connectors30, the switch casing construction 20 and the plug-in construction 22may be secured together, as shown in FIGURE 7 with both the accessopening means 40 and 54 aligned with each other. The gasket 42 coversthe main part of the access openings or opening means 40 and 54 as shownin FIGURE 7, and may be screwed or bolted together by the uniting screws68, which pass through smooth openings 50 and enter the threadedopenings 70 in the switch casing 22. Previously, the mounting screws 72may have been inserted into the internally smooth openings 74 in theplug-in casing 22. The openings 74 are not internally threaded, but theopenings 70 are internally threaded, to receive the threaded ends of theuniting screws 68 which pass through the internally smooth openings 50.The mounting screws 72 are insertable in the openings 74, and thethreaded ends 76 thereof may be screwed or bolted to the mounting boardor surface, not shown. In this manner the plug-in receptacle 22 may bemounted on a board by the screws 72, and thereafter the switch casing 20may be secured to the plug-in casing construction 22 by the unitingscrews 68. During this process of uniting the switch construction 20 andplug-in construction 22, the prong points 66 are inserted through gasketopenings 76 in gasket 42 and into the power line plug-in connectors orprong receiving members 52 which are further to be described. While thisuniting operation is being performed, the casing means securing means orscrews 68 secure the casings together. The switch connector accessopening means 40 and the plug-in access opening means 54 are aligned andheld together with the plug-in change means or prongs 58 passing throughboth of such access openings.

The plug-in casing 22 may also have internally smooth mounting openings75, FIGURES 6 and 12 through which mounting screws, similar to screws72, may be inserted, to secure the plug-in construction 22 by its sideagainst the supporting surface.

The switch casing 20, and the plug-in casing 22 may be substantiallyparallelepipeds with respective access opening means 40 and 54 onrespective sides of such parallelepipeds.

The switch casing 20 may have a switch power line opening means orconduit opening 36 and the plug-in casing 22 may have a plug-in powerline opening 78, FIG- URES 3 and 7. When the casings 20 and 22 are to beunited, as shown in FIGURES 6 and 7, a removable closure member or plugmeans 80, FIGURE 7, may be inserted and sealed in the switch opening 36.Such plug may be sealed by the gasket 38 or by a suitable sealingcompound. At this time, plug-in power line or lines 82, which may becarried by power line conduit 84, may enter the casing 22 through meansopening 78 and may be connected to plug-in power line connectors,connector means, or screws 86, which may be screwed into the bases 88,which are integral with the plug-in connectors or connector means 52 ina manner to be more fully described.

The gasket 42 and the cover or name plate 44 are used over the accessmeans or opening 40 when the switch construction 20 is used alonewithout the plug-in construction 22 as illustrated in FIGURES 1-5.

When the switch construction 20 and the plug-in construction 22 are tobe used together, the name plate 44 is transferred to the side wall 90,FIGURE 7, of the switch construction 20 and is secured thereto by thescrews 92, or by screws 46 which have been removed from their positionin FIGURE 2. The gasket 42 in FIGURE 7, remains against the accessopening 40 of switch construction 20, or is caused to engage such accessopening 40 in the same manner that it engaged such access opening in theconstruction of FIGURES l-5. The access opening 40, FIGURE 2, has acontinuous outward bead 94, FIGURE 2, which is substantially of the samesize and contour as the bead 56, FIGURES 8 and 12, of the access opening'54 of the plug-in construction 22.

When the switch construction 20 and the plug-in construction 22 arebrought together, as shown in FIGURES 6 and 7, the beads 56 and 94 arealigned, and tightly seal. or engage the gasket 42 as is shown in FIGURE7. The permanent prong interlock or electrical interconnector means 52and the plug-in change prong interlock or electrical interconnectormeans 62, 64 and 66 are in engagement with each other in the plug-incasing means 22 with the plug-in change prong interlock or electricalinterconnector means 62, 64, 66 passing through both of said accessopening means 40- and 54.

In order to align the gasket 42 between the openings 40 and 54, theopenings 54, FIGURES 6 and 12, is provided with pegs 96 over which theopenings 97 in the gasket 42 are mounted, as shown in FIGURE 6. The pegs96 are of sufficiently small diameter so that they may be inserted inthe threaded openings 4 The plug-in casing 22, FIGURES 1214, receives amolded insulative cup 98, which has an integral molded insulative bottom100. The bottom 100 has connector receiving openings 102 which receivethe bases 88 of the connecting pieces shown in FIGURE 13. The bases 88and the prong receiving members 52 are parts of one unitary or integralpiece. The openings 102 each have an intermediate wall 104 whichprevents the bases 88 from passing completely through the openings 102in bottom 100, of FIGURE 13. The intermediate wall 104 hasscrew-receiving openings 106 to receive the screw heads of screws 86 andprong-receiving openings or connector-receiving opening 107 to receivethe prong receiving members 52. The prong receiving members orconnectors 52, and the heads of the screws 86 may be insertedrespectively in the openings 107 and 106, so that the connectors 52 andthe screw heads of screws 86 extend into the cup 98 as shown in FIGURE12.

In FIGURE 13, the two upper bases 88 have been inserted in the openings102 and are pressed against the wall 104. The two lower bases 88 ofFIGURE 13 have not been inserted in the openings 102, but they will beinserted therein, as shown by the dotted lines in FIG- URE 13. After allthe bases 88 have been inserted in the openings 102, the connectorholding wall 108, FIG- URE 13, is moved diagonally upward, to engage andhold the bases 88 in place. The protrusions 110, FIG- URE 14, willengage the bases 88, and hold the bases 88 in place.

The retaining wall 108 has forwardly directed ears 112, which haveopenings 114. The openings 114 lock over the slanting tongues 116, whichare shown in FIGURES 12 and 13. This connector holding engagement ofears 112 and tongues 116 will hold wall 108 in position, as shown inFIGURE 12.

In this manner, the complete insulative cup assembly 98, 108 of FIGURE12 is produced, so that the power line plug-in connectors 52 extendoutwardly toward the rim 117 of the cup 98, and are ready to receive theplugin prongs 58 with the prong points 66 entering the connectors 52, asis apparent from FIGURE 6 where the 6 connectors 52 are exposed in theopenings 76 in the gasket 42. Also, the power lines 82, FIGURES 7 and 8,can be attached under the heads of screws 86.

The outside wall of the cup 98 has internally smooth screw-receivingopenings 118, FIGURE 12, which are exposed by the olTset curls 120, sothat the cup-mounting screws 122 may be inserted into the openings 118,and can pass through the openings 124 in the wall 108 and may beinserted into the threaded screw-receiving openings 126, in the casing22, FIGURE 12.

The prong-receiving fork members 52 and bases 88, of FIGURES 12-14 areloosely mounted in the cup 98, so that a slight moving action can takeplace. This insures that the prong points 66 can enter theprong-receiving members 52 without any binding action. The electricalconnection is very good, however, since the current travels from thepower lines 82, FIGURE 7, through the screws and screw heads 86, to thebases 88, and to the prong-receiving members 52. The members 52 and 88are integral so that the current is easily carried.

The protrusions 110, FIGURE 14, have the same general shape as themembers 88, so that these protrusions push the members 88 toward the cup98, when the wall 88 is snapped into position. The protrusions 110 haveopenings 111, which receive the ends of the screws 86 loosely therein.The protrusions 110 fit in the openings 102 fairly snugly, to center theplate or wall 108 against the bottom 100 of the cup 98.

The button 123 engages the bottom 100 of the cup 98 and cooperates withthe ears 112 in maintaining a tight fit between the ears 112 and theslanting tongues 116.

The differently slanted bases 88 aid in maintaining effective contactbetween the prong points 66 and the prong receiving members 52.

Another embodiment of a plug-in receptacle or casing is shown in FIGURE15. In this construction, the metal casing 130 may have the generalfunction and shape of the plug-in casing 22, and may have openings 132to receive screws corresponding to screws 68 of FIGURE 6 and may haveopenings 134 to receive screws corresponding to screws 72 of FIGURE 6.That is, openings 132 correspond to openings 70 of FIGURE 6, andopenings 134 correspond to openings 74 of FIGURE 6. An opening 136 maycorrespond to power line opening 78, of FIGURE 7, through which powerlines 82 may pass to be attached to the retaining screws 86A which areinserted in the prong-carrying plate 138. The plate 138 may be rivetedat 140 into the bottom 142 of the insulative cup 144. The prong-carryingplate 138 may have attached thereto prong receiving fork members 52A,which correspond to connectors 52 of the previous figures. The forkmembers 52A are carried sufiiciently loosely by the prong carrying plate138 to accommodate slight variations in the assembly of the prong points66. Three similar prong receiving members 52A may be connected andcarried by similar prong-carrying plates similar to plate 138. In thismanner, power lines corresponding to power lines 82 of FIGURE 7 may beattached to the power line connectors or screws 86A, in the same mannerthat power lines 82, FIGURE 7, are attached to the power line connectorsor screws 86 of the bases 88 of FIGURE 7. A gasket 44A may be placedover the access opening of the casing 130. The gasket 44A may haveopenings 76A through which the prong points 66 may pass.

Any type of switch construction may be placed in the casing 20. However,merely by way of example, the switch construction disclosed in theapplication of Werner Robert Bauer, Ser. No. 493,108, filed'Oct. 5,1965, now Patent No. 3,317,697, patented May 2, 1967, may be used.Reference is made to such application, if necessary, for furtherdescription of the switch construction per so. In general, the switchmay have a snap-acting blade construction 150, FIGURE 4, which hasdouble movable contacts 152 at each end of the blade 150. These contacts152 engage the stationary contacts 154. The stationary contacts 154 arecarried by sheet metal angle members 156, which are riveted to metalconductors 158, FIGURE 5. These metal conductors 158 have threadedopenings 160, which receive the screws 162, which have the screw heads30 to which the power lines 32 are connected. The metal conductors 158are embedded in the insulative switch casing 164. The casing 164 has thedownward extension 166 through which a mounting screw 168 may beinserted and may be secured to the rear wall 90 of the casing 20. Thecasing 164 has a cover 170, which is hermetically sealed to the casing164 by the flexible gasket 172. The cover 170 has an extension 173 whichmatches extension 166 and through which the screw 168 passes. The entireswitch casing 20 may be hermetically sealed, as more fully described insaid copending application Ser. No. 493,108.

The operating means 28 may be of the character more fully described anddisclosed in the application of William J. Russell, Ser. No. 299,612,filed Aug. 2, 1963, now Patent No. 3,252,345, patented May 24, 1966, towhich reference is made, if necessary, for a further description of theoperating means extending from the casing 20.

Thus a switch construction 20 is provided with an access opening 40which is hermetically closed by name plate or cover 44 and gasket 42.Also, a plug-in receptacle 22 is provided with an access opening 54. Thename plate or cover 44 may be removed from opening 40 and may be mountedn the rear wall 90 of the switch casing 20. Then the switch constructionand the plug-in casing 22 may be united with the access openings 40 and54 aligned and sealed by the gasket 42. The switch actuator 26 isflexibly hermetically sealed as disclosed in said copending aplication493,108. The opening 36 is sealed either by the conduit 34 or the plug80. The opening 78 is sealed by the conduit 84 and the operating means28 is sealed where it connects the actuating means 26. Hence the switchcasing 20 is sealed when used alone, and the casings 20 and 22 aresealed when they are used together.

Thus the switch construction 20 may be used by itself with the coverover the access opening 40 or it may be plugged in to the plug-inreceptacle 22 with plug-in change means or prongs electrically unitingthe receptacles 20 and 22, in a very efficient manner.

While the form of the invention now preferred has been disclosed asrequired by statute, other forms may be used, all coming within thescope of the claimed subject matter which follows.

What is claimed is:

1. In combination: a switch casing means to cooperate in saidcombination; a switch means in said switch casing means to operate insaid switch casing means; switch access opening means on said switchcasing means, said switch access opening means being subtantially flat,and said switch means being entirely inside said switch casing means; aplug-in casing means to be connected with said switch casing means;permanent prong interlock means in said plug-in casing means receivingand connecting with plug-in change prong interlock means; plug-in powerline connecting means on said permanent prong interlock means to connectsaid permanent prong interlock means to said plug-in power lines;substantially flat plug-in access opening means on said plug-in casingmeans for plugin access to said permanent prong interlock means in saidplug-in casing; plug-in change prong interlock means connecting withsaid permanent prong interlock means; and switch casing means andplug-in casing means securing means securing said switch casing meansand said plug-in casing means together with said switch access openingmeans and said plug-in access opening means aligned together, and withsaid plug-in change prong interlock means and said permanent pronginterlock means in engagement with each other in said plug-in casingmeans and with said plug-in change prong interlock means passing throughboth of said access opening means to cause said plug-in power lines tobe controlled by said switch means.

2. A combination according to claim 1 in which'said plug-in change pronginterlock means includes at least one prong construction, each with athreaded portion at one end, a prong point at the other end, and anintermediate turning means between said threaded portion and said prongpoint.

3. A combination according to claim 1 in which said plug-in casing meanshas mounting screw receiving opening means for mounting said plug-incasing means on a supporting surface by means of mounting screws; andsaid switch casing means has mounting screw receiving opening means formounting said switch casing means on said plug-in casing.

4. A combination according to claim 1 in which said permanent interlockmeans in said plug-in casing means includes prong receiving fork membersloosely mounted in said plug-in casing.

5. In combination:

a plug-in casing means (22) to cooperate in said combination;

permanent prong interlock means (52) in said plug-in casing means (22)to connect with plug-in change prong interlock means;

plug-in power line connecting means (86) on said permanent pronginterlock means (52) electrically to connect plug-in power lines (82) tosaid permanent prong interlock means;

substantially fiat plug-in access opening means (54) on said plug-incasing means (22) for plug-in access to said permanent prong interlockmeans (52);

a switch casing means (20) to cooperate in said combination;

a switch means (24) in said switch casing means (20) having electricalcontacts (152, 154) to open and close an electrical circuit;

a plurality of power conductor connecting means (158) on said switchmeans (24) electrically connected to said contacts (152, 154);

a plurality of plug-in change prong interlock means (58) removablyconnected to said plurality of conductor connecting means (158) andinsertable into and connecting with said permanent prong interlock means(52);

substantially fiat switch access opening means (40) on said switchcasing means (20) for access to said change prong interlock means (58)and for interengagement with said plug-in access opening means andcasing means securing means (68) to secure said switch casing means (20)and said plug-in casing means (22) together with said substantially fiatswitch access opening means (40) and said substantially flat plug-inaccess opening means (54) aligned together, and with said plug-in changeprong interlock means (58) and said permanent prong interlock means (52)in engagement with each other in said plug-in casing means through bothof said access opening means to cause said plug-in power lines (82) tobe controlled by said switch means.

6. A combination according to claim 5 in which a cover means (44) is tobe used as a name plate (44) on a side wall of said switch casing means.

7. A combination according to claim 5 in which each of said conductiveconnecting means (153) is an internally threaded opening means (160) andin which each of said plug-in change prong interlock means (58) has athreaded portion means (62) atone end inserted in said internallythreaded means (160) an intermediate turning portion means (64) to beturned by a tool, and prong point means (66) at the other end, so thatsaid prong point means (66) is inserted in said permanent pronginterlock means (52) when said casing are secured together.

8. A combination according to claim 7 in which each of said permanentprong interlock means (52) is a prong receiving fork member means :witha power line connector screw head (86) accessible from said plug-inaccess opening means (54) to receive said prong point means (66).

9. A combination according to claim in which said plug-in casing means(22) and said switch casing means (20) are each substantiallyparallelepipeds with abutting, substantially equal parallelogram sideswith respective abutting relatively large plug-in access opening means(54) and switch access opening means (40) and in which screw receivingopening means (50), (70), (74) proyided adjacent the corners of saidparallelepipeds to receive screws to attach said plug-in casing means(22) and said switch casing means (20) together, to mount said plug-incasing (22) to a support, and mount said switch casing (20) to asupport.

10. In combination:

a plug-in casing means to cooperate in said combination;

permanent electrical interconnector means in said plugin casing means toconnect with plug-in change electrical interconnector means;

plug-in power line connecting means on said permanent electricalinterconnector means electrically to connect plug-in power lines to saidpermanent electrical interconnector means;

substantially flat plug-in access opening means on said plug-in casingmeans for plug-in access to said permanent electrical interconnectormeans;

a switch casing means .to cooperate in said combination;

a switch means in said switch casing means having electrical contacts toopen and close an electrical circuit;

a plurality of power conductor connecting means on said switch meanselectrically connected to said contacts;

a plurality of plug-in change electrical interconnection means removablyconnected to said plurality of conductor connecting means and insertableinto and connecting with said permanent electrical interconector means;

substantially flat switch access opening means on said switch casingmeans for access to said change electrical interconnector means and forinter-engagement with said substantially flat plug-in access openingmeans;

and casing means securing means securing said switch casing means andsaid plug-in casing means together with said substantially flat switchaccess opening means and said substantially flat plug-in access openingmeans aligned together, and with said plug-in change electricalinterconnector means and said permanent electrical interconnector meansin engagement with each other in said plug-in casing means and with saidplug-in change electrical interconnector means passing through both ofsaid access opening means to cause said plug-in power lines to becontrolled by said switch means.

11. In combination:

a switch construction; a plug-in casing; plug-in prong interlock meansin said plug-in casing; plug-in power supply connecting means on saidplug-in prong interlock means; plug-in access opening means on saidplug-in casing providing access to said plug-in prong interlock means,said plug-in casing being in the form of a plugin casing cup bottom anda plug-in casing cup side wall construction forming a plug-in casing rimwhich forms said plug-in access opening means receiving a mating switchcasing access opennig means of said switch construction which has aswitch casing which is similarly shaped in the form of a switch casingcup bottom and a switch casing cup side wall construction forming saidmating switch casing access opening means, and which said switchconstruction has a switch means entirely within said switch casingopening means and with mating interchangeable switch prong interlockmeans interlocking with said plug-in prong interlock means, said switchcasing has a flat name plate secured on the outside of said switch cupbottom by plate fastening means attached to said switch casing cupbottom, said interchangeable prong interlock means having removablescrew means which are removable from said switch construction saidplug-in access opening means also providing access to said plug-in powersupply connecting means for connecting and disconnecting said powersupply to said power supply connecting means on said plug-in interlockmeans, said plug-in casing having a second access opening means tointroduce plug-in power supply'conductor means for connection to saidplug-in power supply connecting means on said plug-in prong interlockmeans, and securing means securing said switch construction and saidplug-in casing together.

12. A combination according to claim 11 in which a resilient flat sheetcover seal member is placed over said access opening means of saidplug-in casing to be engaged by said casing access opening means of saidswitch construction.

13. A combination according to claim 12 in which each of said respectiveaccess opening means has a mating flat head to engage and hold saidresilient sheet cover seal member.

References Cited UNITED STATES PATENTS 3,317,697 5/ 1967 Bauer.

2,494,428 1/1950 Buck 339-- 2,806,912 9/1957 Pearson et al 200-4682,916,591 12/1959 Benn 200-168 2,942,227 6/1960 Hjelseth 339-1203,067,362 12/1962. Patton 317-120 3,122,681 2/1964 Pusch 317--1203,158,703 11/ 1964 De Smidt 20051 ROBERT K. SCHAEFER, Primary Examiner.H. O. JONES, Assistant Examiner.

